I played more in the last two days after making this team than in the month before. Play the pokemon that you like folks. It's a game!
It seems you can't get demoted out of a tier, only the divisions within the tier. So Ive been using it as a perfect chance to try out all the teams and Pokemon, just to get a better sense of their strengths and weaknesses, moves, speed, etc.
I've only had the game for a few days but it seems like a great way to accelerate learning overall. I definitely don't want to just go all in on one team and that's all I know, feel like building up the knowledge base is more critical first.